Apparatus and methods for monitoring physiological data during environmental interference

ABSTRACT

Apparatus and methods for attenuating environmental interference are described. A wearable monitoring apparatus includes a housing configured to be attached to the body of a subject and a sensor module that includes an energy emitter that directs energy at a target region of the subject, a detector that detects an energy response signal—or physiological condition—from the subject, a filter that removes time-varying environmental interference from the energy response signal, and at least one processor that controls operations of the energy emitter, detector, and filter.

RELATED APPLICATION

This application claims the benefit of and priority to U.S. ProvisionalPatent Application No. 61/436,664 filed Jan. 27, 2011, the disclosure ofwhich is incorporated herein by reference as if set forth in itsentirety.

FIELD OF THE INVENTION

The present invention relates generally to monitoring apparatus andmethods and, more particularly, to physiological monitoring apparatusand methods.

BACKGROUND OF THE INVENTION

There is growing market demand for personal health and environmentalmonitors, for example, for gauging overall health, fitness, metabolism,and vital status during exercise, athletic training, work, public safetyactivities, dieting, daily life activities, sickness, and physicaltherapy. However, traditional wearable health monitors cannot measurephysiological information accurately in typical daily environments. Forexample, environmental interference from sunlight, temperature changes,and motion-coupled environmental noise can present measurement artifactson wearable health monitors. These measurement artifacts can reducesensor accuracy, generate false measurements, and prevent accuratehealth, fitness, and vital status monitoring. As such, improved ways ofremoving or preventing environmental interference from measurementstaken from wearable sensors are needed.

SUMMARY

It should be appreciated that this Summary is provided to introduce aselection of concepts in a simplified form, the concepts being furtherdescribed below in the Detailed Description. This Summary is notintended to identify key features or essential features of thisdisclosure, nor is it intended to limit the scope of the invention.

According to some embodiments of the present invention, a medium (e.g.,physiological material of a subject), having a region of interest, ismonitored via a sensor module having at least one energy emitter forinterrogating the medium with energy to generate an energy responseassociated with the medium, at least one circuit to drive at least oneenergy emitter, at least one detector for detecting the energy responseassociated with the medium, a filter that removes time-varyingenvironmental interference from the energy response signal, and aprocessor that controls operations of the energy emitter, detector, andfilter.

According to some embodiments of the present invention, a wearablemonitoring apparatus includes a housing (e.g., an earpiece, earbud,etc.), and a sensor module disposed within or attached to the housing.The housing is configured to be attached to a body of a subject, forexample the ear. The sensor module includes an energy emitter, adetector, a filter, and at least one processor. The energy emitterdirects energy (e.g., optical energy, acoustic energy, ultrasonicenergy, electromagnetic radiation, electrical energy, mechanical energy,magnetic energy, nuclear energy, etc.) at a target region of the subjectand the detector detects an energy response signal from the subject. Theenergy response signal is associated with a physiological condition ofthe subject (e.g., heart rate, pulse pressure, respiration rate, lacticthreshold, blood pressure, volume of blood flow through a blood vessel,blood metabolite level, blood oxygen level, size of at least one bloodvessel, etc.). The filter removes or attenuates time-varyingenvironmental interference from the energy response signal, wherein thetime-varying environmental interference is caused by one or more of thefollowing: sunlight, ambient light, airflow, temperature, etc.

The at least one processor controls operations of the energy emitter,detector, and/or filter. In some embodiments of the present invention,the at least one processor is configured to process the detected energyresponse signal and produce an extracted energy response signal.

In some embodiments of the present invention, the energy emitter emitspulsed or modulated energy.

In some embodiments of the present invention, the energy emittercomprises at least one optical emitter, and the detector comprises atleast one optical detector. Exemplary optical emitters include, but arenot limited to, laser diodes (LDs), light-emitting diodes (LEDs), andorganic light-emitting diodes (OLEDs). Exemplary optical detectorsinclude, but are not limited to, photodetectors, photodiodes,phototransistors, photoactive resistors, photomultiplier tubes,photomultiplier diodes, photodetector modules, and the like.

In some embodiments of the present invention, at least one portion ofthe housing comprises optically transmissive material through whichlight from the at least one optical emitter can pass. In someembodiments of the present invention, at least one portion of thehousing comprises material configured to attenuate (e.g., reduce orblock) light reaching the at least one optical detector at one or moreselected wavelengths.

In some embodiments of the present invention, the monitoring apparatusincludes at least one analog-to-digital (ADC) converter that convertsanalog signals generated by the detector to digital signals.

According to some embodiments of the present invention, a monitoringapparatus includes a housing configured to be attached to the ear of asubject, and a sensor module disposed within or attached to the housing.The sensor module includes an optical emitter, a detector, amotion/position sensor, a filter, and at least one processor thatcontrols operations of the optical emitter, detector, and/or filter. Theoptical emitter directs optical energy at a target region of the subjectand the detector detects an optical energy response signal from thesubject, wherein the energy response signal is associated with aphysiological condition of the subject. Light-opaque material surroundsat least part of the sensor module to prevent ambient light frominterfering with the detector. Output from the motion/position sensor isassociated with the motion or position between the housing and ear ofthe subject. The filter removes or attenuates time-varying environmentalinterference from the optical energy response signal, wherein thetime-varying environmental interference is caused by one or more of thefollowing: sunlight, ambient light, airflow, and temperature.

According to some embodiments of the present invention, a sensor moduleincludes a printed circuit board (PCB), in some cases having oppositefirst and second sides, an optical emitter attached to at least one sideof the PCB, an optical detector attached to at least one side of the PCBadjacent to the optical emitter, an optical filter overlying at least aportion of the optical detector, and light-opaque material adjacent tothe optical detector. The optical filter is configured to attenuate(e.g., reduce or block) light at one or more selected wavelengths, andthe light-opaque material prevents ambient light from interfering withthe optical detector.

In some embodiments of the present invention, the optical filter has asurface area greater than a surface area of the optical detector, andthe optical filter overlies the optical detector such that a peripheryof the optical filter overlaps a periphery of the optical detector.

In some embodiments of the present invention, light-opaque materialsurrounds the optical emitter and optical detector such that the opticalemitter and optical detector are not in direct optical communicationwith each other. In some embodiments of the present invention, thelight-opaque material includes a first aperture in communication withthe optical emitter, and a second aperture in communication with theoptical detector.

In some embodiments of the present invention, the sensor module includesa lens positioned above at least one of the optical emitter and filter.The lens may include respective first and second portions configured tomatingly engage respective first and second apertures in thelight-opaque material.

In other embodiments of the present invention, a first lens ispositioned within the first aperture and is in optical communicationwith the optical emitter, and a second lens is positioned within thesecond aperture and is in optical communication with the opticaldetector. The first lens focuses light emitted by the optical emitterand the second lens focuses light toward the optical detector.

In some embodiments of the present invention, a second optical detectoris attached to the PCB second side.

According to other embodiments of the present invention, an earbud for aheadset includes a housing that is configured to be positioned within anear of a subject, a speaker, and at least one sensor module disposedwithin or attached to the housing. The at least one sensor moduleincludes a printed circuit board (PCB) having opposite first and secondsides, an optical emitter attached to at least one side of the PCB thatdirects electromagnetic radiation at a target region of the ear, anoptical detector attached to at least one side of the PCB adjacent tothe optical emitter that detects an energy response signal associatedwith a physiological condition of the subject from the subject, and anoptical filter overlying at least a portion of the optical detector,wherein the optical filter is configured to attenuate (e.g., reduce orblock) light at one or more selected wavelengths. A filter may beincluded that removes time-varying environmental interference from theenergy response signal. Time-varying environmental interference may becaused by one or more of the following: sunlight, ambient light,airflow, temperature, etc. The at least one sensor module may include atleast one processor that controls operations of the optical emitter,optical detector, and/or filter.

In some embodiments of the present invention, the optical filter has asurface area greater than a surface area of the optical detector, andthe optical filter overlies the optical detector such that a peripheryof the optical filter overlaps a periphery of the optical detector.

In some embodiments of the present invention, light-opaque materialsurrounds the optical emitter and optical detector such that the opticalemitter and optical detector are not in direct optical communicationwith each other. In some embodiments of the present invention, thelight-opaque material includes a first aperture in communication withthe optical emitter, and a second aperture in communication with theoptical detector.

In some embodiments of the present invention, the at least one sensormodule include a lens positioned above at least one of the opticalemitter and filter. The lens may include respective first and secondportions configured to matingly engage respective first and secondapertures in the light-opaque material.

In other embodiments of the present invention, a first lens ispositioned within the first aperture and is in optical communicationwith the optical emitter, and a second lens is positioned within thesecond aperture and is in optical communication with the opticaldetector. The first lens focuses light emitted by the optical emitterand the second lens focuses light toward the optical detector.

In some embodiments of the present invention, a second optical detectoris attached to the PCB second side.

In some embodiments of the present invention, one or more portions ofthe earbud housing include optically transmissive material through whichlight from the optical emitter can pass.

In some embodiments of the present invention, one or more portions ofthe housing include material configured to attenuate (e.g., reduce orblock) light reaching the optical detector at one or more selectedwavelengths.

In some embodiments of the present invention, the at least one sensormodule includes an analog-to-digital (ADC) converter that convertsanalog signals generated by the optical detector to digital signals.

In some embodiments of the present invention, the at least one sensormodule includes at least one motion/position sensor attached to at leastone side of the PCB.

In some embodiments of the present invention, the at least one sensormodule housing includes a soft material which deforms when insertedwithin an ear and that facilitates retention of the earbud within anear. In other embodiments, the at least one sensor module housing has ashape that facilitates retention of the earbud within an ear.

In some embodiments of the present invention, a portion of the at leastone sensor module housing includes optically transmissive materialthrough which light from the optical emitter can pass, and wherein thehousing includes a soft material adjacent to the optically transmissivematerial which deforms when inserted within an ear and that facilitatesretention of the earbud within an ear.

In some embodiments of the present invention, a portion of the at leastone sensor module housing includes material configured to diffuse lightfrom the optical detector and/or diffuse light to the optical detector.

In some embodiments of the present invention, the at least one sensormodule comprises two sensor modules in spaced apart relationship.

According to other embodiments of the present invention, a method ofmonitoring at least one physiological property of a subject includesdirecting pulsed energy at a target region of the subject via an energyemitter, obtaining a first energy response signal from the subject whenthe emitter is on, obtaining a second energy response signal from thesubject when the emitter is off, and processing the first and secondenergy response signals via an interference filter to produce aprocessed energy response signal that is associated with a physiologicalcondition (e.g., heart rate, pulse pressure, respiration rate, lacticthreshold, blood pressure, volume of blood flow through a blood vessel,blood metabolite level, blood oxygen level, size of at least one bloodvessel, etc.) of the subject, wherein the filter removes or attenuatestime-varying environmental interference caused by one or more of thefollowing: sunlight, ambient light, airflow, temperature, etc. Directingpulsed energy at a target region may include directing energy selectedfrom the group consisting of optical energy, acoustic energy, ultrasonicenergy, electromagnetic radiation, electrical energy, magnetic energy,mechanical energy, nuclear energy, etc.

In some embodiments of the present invention, the interference filteremploys a spectral method to remove or attenuate time-varyingenvironmental interference. In some embodiments of the presentinvention, the interference filter employs an FIR filtering method toremove or attenuate time-varying environmental interference.

In some embodiments of the present invention, the processed energyresponse signal is transmitted to a remote device, for examplewirelessly transmitted.

In some embodiments of the present invention, the environmentalinterference may comprise ambient light, sunlight, room light, wind,sound, mechanical interference, electrical interference, temperaturechanges, or the like.

In some embodiments of the present invention, the geometricalconfiguration of an emitter and detector may be oriented to maximize thecollection of the energy response signal associated with physiologicalconditions and to minimize the collection of the unwanted scatteredlight response.

In some embodiments, multiple emitters, detectors, lenses, light guides,and/or diffusion regions may be employed within a sensor module.

Emitters and detectors, according to some embodiments of the presentinvention, may be configured to generate a more universal earbud sensordesign. In some embodiments, this may be achieved by employing adiffusion area.

In some embodiments of the present invention, an earbud may comprise aninterchangeable tip, wherein optical coupling may be integrated withinthe earbud to communicate light to/from the ear region through theinterchangeable tip.

In some embodiments of the present invention, a physiological conditionmonitored, such as heart rate, for example, may be modulated to improvefiltering and then demodulated to generate the desired output.

In some embodiments of the present invention, an interference filter mayemploy at least one motion/position sensor to remove interference from adesired physiological signal, such as to remove motion-coupled sunlightinterference from a heart rate signal.

According to some embodiments of the present invention, a wearablemonitoring apparatus includes a substrate configured to be attached to abody of a subject, and a sensor module attached to the substrate. Thesubstrate may be configured to surround a portion of a body, and may beflexible. For example, the substrate may be a wristband, armband,legband, neckband, waistband, ankleband, footband, handband, ringband,headband, etc. In other embodiments, the substrate is configured to beadhesively attached to the body of the subject, similar to a bandage.

The sensor module includes an energy emitter, a detector, a filter, andat least one processor. The energy emitter directs energy (e.g., opticalenergy, acoustic energy, ultrasonic energy, electromagnetic radiation,electrical energy, mechanical energy, magnetic energy, nuclear energy,etc.) at a target region of the subject and the detector detects anenergy response signal from the subject. The energy response signal isassociated with a physiological condition of the subject (e.g., heartrate, pulse pressure, respiration rate, lactic threshold, bloodpressure, volume of blood flow through a blood vessel, blood metabolitelevel, blood oxygen level, size of at least one blood vessel, etc.). Thefilter removes or attenuates time-varying environmental interferencefrom the energy response signal, wherein the time-varying environmentalinterference is caused by one or more of the following: sunlight,ambient light, airflow, temperature, etc.

The at least one processor controls operations of the energy emitter,detector, and/or filter. In some embodiments of the present invention,the at least one processor is configured to process the detected energyresponse signal and produce an extracted energy response signal.

In some embodiments of the present invention, the energy emitter emitspulsed or modulated energy.

In some embodiments of the present invention, the energy emittercomprises at least one optical emitter, and the detector comprises atleast one optical detector. Exemplary optical emitters include, but arenot limited to, LDs, LEDs, and OLEDs. Exemplary optical detectorsinclude, but are not limited to, photodetectors, photodiodes,phototransistors, photoactive resistors, photomultiplier tubes,photomultiplier diodes, photodetector modules, and the like.

In some embodiments of the present invention, the apparatus includesoptically transmissive material through which light from the at leastone optical emitter can pass. In some embodiments of the presentinvention, the apparatus includes material configured to attenuate(e.g., reduce or block) light reaching the at least one optical detectorat one or more selected wavelengths.

In some embodiments of the present invention, the monitoring apparatusincludes at least one ADC converter that converts analog signalsgenerated by the detector to digital signals.

The detectors that may be incorporated into headsets, earbuds, and/orsubstrates (e.g., wristbands, armbands, legbands, neckbands, waistbands,anklebands, footbands, handbands, ringbands, headbands, etc.) accordingto some embodiments of the present invention, may be configured todetect and/or measure one or more of the following types ofphysiological information/conditions: heart rate, pulse rate, breathingrate, blood flow, VO₂, VO₂max, heartbeat signatures, cardio-pulmonaryhealth, organ health, metabolism, electrolyte type and/or concentration,physical activity, caloric intake, caloric metabolism, blood metabolitelevels or ratios, blood pH level, physical and/or psychological stresslevels and/or stress level indicators, drug dosage and/or dosimetry,physiological drug reactions, drug chemistry, biochemistry, positionand/or balance, body strain, neurological functioning, brain activity,brain waves, blood pressure, cranial pressure, hydration level,auscultatory information, auscultatory signals associated withpregnancy, physiological response to infection, skin and/or core bodytemperature, eye muscle movement, blood volume, inhaled and/or exhaledbreath volume, physical exertion, exhaled breath physical and/orchemical composition, the presence and/or identity and/or concentrationof viruses and/or bacteria, foreign matter in the body, internal toxins,heavy metals in the body, anxiety, fertility, ovulation, sex hormones,psychological mood, sleep patterns, hunger and/or thirst, hormone typeand/or concentration, cholesterol, lipids, blood panel, bone density,organ and/or body weight, reflex response, sexual arousal, mental and/orphysical alertness, sleepiness, auscultatory information, response toexternal stimuli, swallowing volume, swallowing rate, sickness, voicecharacteristics, voice tone, voice pitch, voice volume, vital signs,head tilt, allergic reactions, inflammation response, auto-immuneresponse, mutagenic response, DNA, proteins, protein levels in theblood, water content of the blood, pheromones, internal body sounds,digestive system functioning, cellular regeneration response, healingresponse, stem cell regeneration response, etc.

It is noted that aspects of the invention described with respect to oneembodiment may be incorporated in a different embodiment although notspecifically described relative thereto. That is, all embodiments and/orfeatures of any embodiment can be combined in any way and/orcombination. Applicant reserves the right to change any originally filedclaim or file any new claim accordingly, including the right to be ableto amend any originally filed claim to depend from and/or incorporateany feature of any other claim although not originally claimed in thatmanner. These and other objects and/or aspects of the present inventionare explained in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which form a part of the specification,illustrate various embodiments of the present invention. The drawingsand description together serve to fully explain embodiments of thepresent invention.

FIG. 1 schematically illustrates an interference filtering apparatus andmethod, according to some embodiments of the present invention.

FIG. 2 illustrates a multi-wavelength reflection-mode pulse oximetryapparatus that may be utilized in accordance with some embodiments ofthe present invention.

FIG. 3 illustrates various types of time-varying environmentalinterference.

FIG. 4A is a side view of a human ear with an earbud monitor, accordingto some embodiments of the present invention, inserted therein.

FIG. 4B is a front view of a human ear with an earbud monitor, accordingto some embodiments of the present invention, inserted therein.

FIG. 5 is a schematic illustration of how external light interferencecan pass through a human ear and reach an optical detector in an earbudmonitor attached to the ear.

FIG. 6 is a comparison graph showing optical detector intensity vs.wavelength for direct sunlight exposure and indirect sunlight exposurecaused by scattering through the ear region.

FIG. 7 illustrates a sensor module with a convex lens configuration,according to some embodiments of the present invention.

FIG. 8 illustrates a sensor module with a concave lens configuration,according to some embodiments of the present invention.

FIG. 9A is a rear perspective view of an earbud monitor, according tosome embodiments of the present invention.

FIG. 9B is a front perspective view of the earbud monitor of FIG. 9A.

FIG. 10 illustrates the angling preferences for sensor modules within anearbud monitor, according to some embodiments of the present invention.

FIG. 11 illustrates an earbud monitor, according to some embodiments ofthe present invention, that increases physiological signal and reducesenvironmental noise.

FIG. 12A is a perspective view of a sensor module, according to someembodiments of the present invention.

FIG. 12B is a side view of the sensor module of FIG. 12A.

FIG. 12C is a top plan view of the sensor module of FIG. 12A.

FIG. 13A is a side view of an earbud comprising the sensor module ofFIGS. 12A-12C, according to some embodiments of the present invention.

FIG. 13B is a front perspective view of the earbud of FIG. 13A.

FIG. 13C is a side perspective view of the earbud of FIG. 13A.

FIG. 14 is a bottom perspective view of a multi-detector earbud,according to some embodiments of the present invention.

FIG. 15A is a side perspective view of a multi-detector earbudcomprising two separate optical coupling areas, according to someembodiments of the present invention.

FIG. 15B is a bottom plan view of the earbud of FIG. 15A.

FIG. 16A is an exploded side view of a headphone and areplaceable/interchangeable earbud tip, according to some embodiments ofthe present invention.

FIG. 16B is an exploded side view of a headphone and areplaceable/interchangeable earbud tip, according to other embodimentsof the present invention.

FIG. 17 is a rear view of the earbud tip of FIG. 16B taken along lines17-17, and illustrating at least two separate parts supporting at leasttwo separate optical paths.

FIG. 18 is a flowchart of operations for removing environmental noisefrom a sensor signal, according to some embodiments of the presentinvention.

FIGS. 19A and 19B are graphs illustrating digital sampling of a detectorsignal, according to some embodiments of the present invention.

FIG. 20 is a schematic illustration of an interference filter, accordingto some embodiments of the present invention.

FIG. 21 is a graph that illustrates magnitude responses for severalinterference filters, according to some embodiments of the presentinvention.

FIGS. 22A-22D are graphs of the processed heart rate signal output of anearbud module employing two different filter configurations, accordingto some embodiments of the present invention.

FIG. 23 is a perspective view of a monitoring apparatus including asensor module of FIG. 7 or FIG. 8, according to some embodiments of thepresent invention, and wherein the monitoring apparatus is adapted tofit around a wrist of a person.

FIG. 24 is a side view of the monitoring apparatus of FIG. 23.

FIG. 25 is a plan view of the sensor module of the monitoring apparatusof FIG. 23.

FIG. 26 is an enlarged plan view of the sensor module of the monitoringapparatus of FIG. 23.

FIG. 27 is an enlarged side view of the sensor module of the monitoringapparatus of FIG. 23.

FIG. 28 illustrates the sensor module of the monitoring apparatus ofFIG. 23 in contact with the skin of a subject.

FIG. 29 is an enlarged side view of the sensor module of the monitoringapparatus of FIG. 23, according to other embodiments of the presentinvention.

DETAILED DESCRIPTION

The present invention will now be described more fully hereinafter withreference to the accompanying figures, in which embodiments of theinvention are shown. This invention may, however, be embodied in manydifferent forms and should not be construed as limited to theembodiments set forth herein. Like numbers refer to like elementsthroughout. In the figures, certain layers, components or features maybe exaggerated for clarity, and broken lines illustrate optionalfeatures or operations unless specified otherwise. In addition, thesequence of operations (or steps) is not limited to the order presentedin the figures and/or claims unless specifically indicated otherwise.Features described with respect to one figure or embodiment can beassociated with another embodiment or figure although not specificallydescribed or shown as such.

It will be understood that when a feature or element is referred to asbeing “on” another feature or element, it can be directly on the otherfeature or element or intervening features and/or elements may also bepresent. In contrast, when a feature or element is referred to as being“directly on” another feature or element, there are no interveningfeatures or elements present. It will also be understood that, when afeature or element is referred to as being “connected”, “attached” or“coupled” to another feature or element, it can be directly connected,attached or coupled to the other feature or element or interveningfeatures or elements may be present. In contrast, when a feature orelement is referred to as being “directly connected”, “directlyattached” or “directly coupled” to another feature or element, there areno intervening features or elements present. Although described or shownwith respect to one embodiment, the features and elements so describedor shown can apply to other embodiments. It will also be appreciated bythose of skill in the art that references to a structure or feature thatis disposed “adjacent” another feature may have portions that overlap orunderlie the adjacent feature.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, steps, operations, elements, components, and/or groupsthereof. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items.

Spatially relative terms, such as “under”, “below”, “lower”, “over”,“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if a device in thefigures is inverted, elements described as “under” or “beneath” otherelements or features would then be oriented “over” the other elements orfeatures. Thus, the exemplary term “under” can encompass both anorientation of over and under. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly. Similarly, the terms“upwardly”, “downwardly”, “vertical”, “horizontal” and the like are usedherein for the purpose of explanation only unless specifically indicatedotherwise.

It will be understood that although the terms first and second, and thelike, are used herein to describe various features/elements, thesefeatures/elements should not be limited by these terms. These terms areonly used to distinguish one feature/element from anotherfeature/element. Thus, a first feature/element discussed below could betermed a second feature/element, and similarly, a second feature/elementdiscussed below could be termed a first feature/element withoutdeparting from the teachings of the present invention.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the specification andrelevant art and should not be interpreted in an idealized or overlyformal sense unless expressly so defined herein. Well-known functions orconstructions may not be described in detail for brevity and/or clarity.

The term “headset” includes any type of device or earpiece that may beattached to or near the ear (or ears) of a user and may have variousconfigurations, without limitation. Headsets as described herein mayinclude mono headsets (one earbud) and stereo headsets (two earbuds),earbuds, hearing aids, ear jewelry, face masks, headbands, and the like.

The term “modulated energy”, as used herein, refers to energy (e.g.,optical energy, acoustic energy, ultrasonic energy, electromagneticradiation, electrical energy, magnetic energy, mechanical energy,nuclear energy, etc.) that is emitted in pulses and/or that is emittedsuch that the amplitude, frequency, phase, or intensity is varied. Apulsed energy source modulates by effectively multiplying by a waveformthat is a periodic sequence of zeros and ones.

The term “real-time” is used to describe a process of sensing,processing, or transmitting information in a time frame which is equalto or shorter than the minimum timescale at which the information isneeded. For example, the real-time monitoring of pulse rate may resultin a single average pulse-rate measurement every minute, averaged over30 seconds, because an instantaneous pulse rate is often useless to theend user. Typically, averaged physiological and environmentalinformation is more relevant than instantaneous changes. Thus, in thecontext of embodiments of the present invention, signals may sometimesbe processed over several seconds, or even minutes, in order to generatea “real-time” response.

The term “monitoring” refers to the act of measuring, quantifying,qualifying, estimating, sensing, calculating, interpolating,extrapolating, inferring, deducing, or any combination of these actions.More generally, “monitoring” refers to a way of getting information viaone or more sensing elements. For example, “blood health monitoring”includes monitoring blood gas levels, blood hydration, andmetabolite/electrolyte levels.

The term “physiological” refers to matter or energy of or from the bodyof a creature (e.g., humans, animals, etc.). In embodiments of thepresent invention, the term “physiological” is intended to be usedbroadly, covering both physical and psychological matter and energy ofor from the body of a creature. However, in some cases, the term“psychological” is called-out separately to emphasize aspects ofphysiology that are more closely tied to conscious or subconscious brainactivity rather than the activity of other organs, tissues, or cells.

The term “body” refers to the body of a subject (human or animal) whomay wear a headset incorporating embodiments of the present invention.

In the included figures, various embodiments will be illustrated anddescribed. However, it is to be understood that embodiments of thepresent invention are not limited to those worn by humans.

The terms “creature” and “subject”, as used herein, are interchangeableand include humans and animals.

The human ear is an ideal location for wearable health and environmentalmonitors. The ear is a relatively immobile platform that does notobstruct a person's movement or vision. Headsets located at an ear have,for example, access to the inner-ear canal and tympanic membrane (formeasuring core body temperature), muscle tissue (for monitoring muscletension), the pinna and earlobe (for monitoring blood gas levels), theregion behind the ear (for measuring skin temperature and galvanic skinresponse), and the internal carotid artery (for measuringcardiopulmonary functioning), etc. The ear is also at or near the pointof exposure to: environmental breathable toxicants of interest (volatileorganic compounds, pollution, etc.); noise pollution experienced by theear; and lighting conditions for the eye. Furthermore, as the ear canalis naturally designed for transmitting acoustical energy, the earprovides a good location for monitoring internal sounds, such asheartbeat, breathing rate, and mouth motion.

Wireless, Bluetooth®-enabled, and/or other personal communicationheadsets may be configured to incorporate physiological and/orenvironmental sensors, according to some embodiments of the presentinvention. As a specific example, Bluetooth® headsets are typicallylightweight, unobtrusive devices that have become widely acceptedsocially. Moreover, Bluetooth® headsets are cost effective, easy to use,and are often worn by users for most of their waking hours whileattending or waiting for cell phone calls. Bluetooth® headsetsconfigured according to embodiments of the present invention areadvantageous because they provide a function for the user beyond healthmonitoring, such as personal communication and multimedia applications,thereby encouraging user compliance. Exemplary physiological andenvironmental sensors that may be incorporated into a Bluetooth® orother type of headsets include, but are not limited to accelerometers,auscultatory sensors, pressure sensors, humidity sensors, color sensors,light intensity sensors, pressure sensors, etc.

Optical coupling into the blood vessels of the ear may vary betweenindividuals. As used herein, the term “coupling” refers to theinteraction or communication between excitation light entering a regionand the region itself. For example, one form of optical coupling may bethe interaction between excitation light generated from within alight-guiding earbud and the blood vessels of the ear. Light guidingearbuds are described in co-pending U.S. Patent Application PublicationNo. 2010/0217102, which is incorporated herein by reference in itsentirety. In one embodiment, this interaction may involve excitationlight entering the ear region and scattering from a blood vessel in theear such that the intensity of scattered light is proportional to bloodflow within the blood vessel. Another form of optical coupling may bethe interaction between excitation light generated by an optical emitterwithin an earbud and the light-guiding region of the earbud.

Embodiments of the present invention are not limited to headsets thatcommunicate wirelessly. In some embodiments of the present invention,headsets configured to monitor an individual's physiology and/orenvironment may be wired to a device that stores and/or processes dataor there may be a combination of wired and wireless communications. Insome embodiments, this information may be stored on the headset itself.Furthermore, embodiments of the present invention are not limited toearbuds. In some embodiments, the invention may be employed aroundanother part of the body, such as a digit, finger, toe, limb, wrist,ankle, around the nose or earlobe, or the like. In other embodiments,the invention may be integrated into a patch, such as a bandage thatsticks on a person's body.

FIG. 1 illustrates an interference filtering apparatus/method 100,according to some embodiments of the present invention. A medium 130,preferably physiological material of a living subject, comprises atleast one target region of interest 120 which is interrogated by energy110, preferably modulated energy, such as pulsed energy, generated by anenergy emitter 102. A pulsed driving circuit 101 is used to drive atleast one energy emitter 102 at one or more pulsed frequencies tointerrogate at least one target region of at least one medium 130 withthe pulsed energy 110. The energy may be in the form of electromagnetic,acoustical, mechanical, nuclear, electrical, magnetic, thermal, or otherforms of energy, but typically optical energy from the electromagneticspectrum. The energy reaching the medium 130 can interact with themedium to generate at least one energy response signal 111, such as anoptical scatter signal 111 between emitted optical energy 110 and themedium 130. The energy response 111 caused by this interaction isdetected by at least one detector 103, configured to detect energy inthe forms described above, but typically in the form of optical energyscattered from the medium 130. A motion/position sensor 104 may beconfigured to measure movement, positional changes, or inertial changesin the vicinity of the medium 130. The outputs of the detector 103 maybe sent to at least one analog-to-digital convertor (ADC) 105 and thedigitized output may be sent to at least one interference filter 106,which is configured to remove the effects of time-varying environmentalinterference 140 from the signal output of the detector 103. At leastone motion/position sensor 104 may be incorporated in the interferencefiltering method 100 to provide a reference signal for removing theeffects of motion from the extracted energy response signal 111 toproduce a desired signal 109. For example, the output of theinterference filter 106 may be further processed by signal extractionfilter 107 to extract accurate information from the medium 130, and thissignal extraction filter 107 may utilize the output of themotion/position sensor 104 to remove motion artifacts from the desiredsignal (the extracted energy response signal) 109. At least one signalprocessor (not shown) may be used to control the operations of theenergy emitter 102, detector 103, filter 106, and/or other components ofthe interference filtering method 100.

In some embodiments of the present invention, a monitoring apparatus isconfigured to be a wearable monitor for monitoring at least onephysiological condition of the wearer. In such an embodiment, pulsedelectromagnetic energy 110 from at least one electromagnetic emitter102, typically an optical emitter, is directed towards at least onephysiological region 130, typically the ear region, of a subject.Examples of optical emitters include light-emitting diodes (LEDs), laserdiodes (LDs), lamps, organic emitters (such as OLEDs), and the like. Thesensor components (102, 103, and 104) may be integrated within the earregion 120 in the form-factor of an earbud or other ear-worn form-factorsuch that the measurement medium 130 comprises blood vessels and/orblood flow within the ear region. The intensity of the pulsed opticalenergy 110 is modulated by at least one pulsed driving circuit 101 suchthat the intensity is time-varying with at least two states, preferablyan on state and an off state. This time-varying energy generates atime-varying energy response, typically an optical interaction response,such as optical absorption, modulation, scatter, transmission,luminescence, or the like, from the physiological region 130. A firstoptical interaction response is obtained by at least one detector 103,typically an optical detector, when the pulsed optical energy 110 is inthe on state. A second energy response, in this case a second opticalinteraction response, is obtained by the optical detector 103 when thepulsed optical energy 110 is in the off state. (In some cases, otheroptical interaction responses may be collected in other modulated statesof the pulsed energy 110.) The first and second energy response signalsare digitized by at least one ADC 105 and the digitized signals areprocessed via an interference filter 106 to produce a processed energyresponse signal that is associated with a physiological condition of thesubject, wherein the filter removes time-varying environmentalinterference caused by an interferant, such as sunlight, ambient light,airflow, temperature, etc. The output of the interference filter 106 isthen processed by a signal extraction filter 107 to accurately extractat least one physiological property of the subject. A motion/positionsensor 104 may be configured to measure the motion/position between themedium 130 and the emitter 102, the detector 103, and/or thetime-varying interference 140, for example, caused by motion of thesubject. The output signal of the motion sensor 104 may provide a motionartifact reference to the signal extraction filter 107 such that themotion/position information may be selectively removed from the desiredsignal output. Incorporating a motion sensor in embodiments of thepresent invention may be particularly important because time-varyinginterference, such as sunlight hitting an earbud, is often modulated bymotion, and monitoring and subtracting this motion from the desiredoutput may be critical to generating an accurate physiological signal inthe midst of daily life activities of the subject.

Various forms of energy 110 can be used to interrogate one or moremediums 130 and to characterize those mediums by detectors 103configured to detect the energy responses caused by the interaction ofthe energy 110 with the medium 130. For example, optical energy 110 canbe used to interrogate a target region of skin and blood 130 to provideinformation regarding a physiological condition of a subject, such as ameasure of blood oxygen levels of the subject by pulse oximetry. Aspecific example of the opto-physiological interaction between light anda physiological medium 130 comprising the skin, blood vessels, and bloodof a subject is shown in the reflective optical detection configuration200 of FIG. 2. At least one sensor module 207, disposed within at leastone housing configured to be attached to a body of a subject, may be inphysical proximity to the skin of the subject, as shown in thereflective pulse oximetry setup 200 where reflected optical wavelengths111 are measured, as opposed to measuring transmitted opticalwavelengths. Optical emitter and optical detector wavelengths for pulseoximetry and photoplethysmography may include virtually any wavelengthof electromagnetic radiation, but particularly useful are UV, visible,and IR wavelengths. In the illustrated embodiment, an opticalsource-detector assembly 201, including an optical emitter 102 andoptical detectors 103, is integrated into sensor module 207 to generateoptical wavelengths 110 and monitor the resulting scattered opticalenergy 111. The optical source-detector assembly 201 may contain one ormore optical sources emitting one or more optical wavelengths, as wellas one or more optical detectors detecting one or more opticalwavelengths. The epidermis 212, dermis 213, and subcutaneous 214 layersof skin tissue of a human are shown in FIG. 2 for reference. Thescattered optical energy 111 may be modulated in intensity by changes inphysiological condition, such as: changes in blood flow in the bloodvessels, changes in physical motion of the body, changes in bloodmetabolite levels (such as blood gases, bilirubin, glucose, lactic acid,and the like), respiration, heart rate, pulse pressure, blood pressure,and other physiological changes. In some cases, the scattered opticalenergy 111 may be luminescent or preferentially polarized energy fromthe skin, blood, blood metabolites, drugs, or other materials in thebody. Thus, the energy response signal 111 may contain informationassociated with at least one physiological condition of the subject.

In real-world environments, the energy response signal 111 collected bya wearable sensor module 207 may be corrupted by time-varyingenvironmental interference 140 (FIG. 1). Moreover, the energy responsesignal 111 may be even further corrupted by motion of the subject in atime-varying environment. For example, the motion caused by running maycause motion with respect to the emitter 102, detector 103, and medium130 (in this case tissue of the subject), and this motion may cause anunwanted signal on the detector 103. Moreover, the time-varyingenvironmental interference 140 (FIG. 1) may be caused by, or exacerbatedby, the motion of the subject. A specific example of time-varyinginterference in a real-world environment 300 is summarized in FIG. 3. InFIG. 3, the runner is wearing an audio headset H containing biometricmonitoring technology, such as Valencell's Healthset® brand technology(Valencell, Inc., Raleigh, N.C.), where at least onephotoplethysmography sensor module 207 (FIG. 2) is included within abiometric audio earbud 404 as shown in FIG. 4. The sensor module 207 maycontain at least one optical emitter 102, at least one optical detector103, and at least one processor to measure heart rate, respiration rate,pulse pressure, motion, and/or other physiological conditions near theear region 130 of the subject. These types of measurements may beachieved by detecting the optical scatter response 111 from the earregion as summarized in FIG. 2. However, direct sunlight SL₁, indirectsunlight SL₂ and/or artificial light AL₁ from the environment may passinto the audio headset H. Time-varying sunlight SL₁, SL₂ and artificialambient light AL₁ may impart time-varying optical interference 140 onthe optical detector 103 embedded within the audio headset H. Forexample, a time-varying interference signal 140 (FIG. 1) fromenvironmental light may impart substantial artifacts on an energyresponse signal 111 (FIG. 1) in many real life scenarios, such as whenclouds pass through the sky, when a subject runs through shadows, when asubject runs to/from an artificial light source, and/or various thereof.These time-varying artifacts may be difficult to distinguish from thedesired time-varying signals associated with time-varying physiologicalconditions. For example, the interference frequencies associated with atime-varying change in shadows, or the harmonics of these interferencefrequencies, may correspond with at least one signal frequencyassociated with footsteps, respiration, or heart rate, and the opticalenergy response 111 may contain convoluted information comprisinginterference signals and desired physiological signals.

The aforementioned time-varying interference signal 140 (FIG. 1) fromdirect sunlight SL₁ during jogging may be considered to be “directinterference”, in that interfering sunlight may be detected directly bythe optical detector 103. However, there may be cases where theinterference may reach the optical detector 103 indirectly, causing thesame signal processing challenges as with direct interference. Forexample, FIG. 5 summarizes how external light EL₁ from the sun or otherexternal source can pass through the ear region and reach the opticaldetector 103 embedded within the sensor module 207. It may be difficultto distinguish this external light from the scattered excitation lightassociated with at least one physiological condition of the subject.

To address these problems, a novel embodiment of the interferencefiltering method and apparatus 100 is to employ both novel filteringmethods and novel optomechanical earbud designs to: 1) remove sunlightfrom the desired signal response 109 (FIG. 1) and 2) prevent sunlightfrom reaching the detector 103 in the first place. Embodiments of thepresent invention described herein employ at least one of theseapproaches, but typically both, to teach how to make a wearable monitor,such as an earbud monitor, that may provide accurate information onphysiological conditions in the midst of environmental noise, such asnoise from ambient light and/or sunlight.

An experiment was performed by the Applicant to address the magnitude ofthe aforementioned sunlight convolution problem for an earbudphysiological monitor. In this experiment, an optical spectrometer wasoptically coupled to a light guide embedded within an earbud worn by asubject in an outdoor sunlight environment. The only light reaching thespectrometer was light guided by an earbud-embedded light guide,positioned in the same basic region as the sensor module 207 shown inFIGS. 4 and 5. Thus, the light guide was guiding light from the earregion on one end towards the input of the spectrometer at the otherend. Because the light guide was covered at one end by the spectrometerand at another end by the ear of the subject, the only significant lightreaching the light guide was light generated by external light EL₁passing through the ear, as shown in FIG. 5. With the earbud worn by thesubject, a first spectrogram was taken of this indirect externalsunlight scattered through the ear. The earbud was then removed andpointed directly at the sun, and a second spectrogram was taken ofdirect sunlight hitting the ear with the earbud directly facing the sunto provide a comparison graph 600, as shown in FIG. 6. The comparisongraph 600 shows that sunlight at wavelengths shorter than 600 nm isgreatly attenuated through the subject's ear, whereas sunlight atwavelengths longer than 650 nm is minimally absorbed through thesubject's ear.

In light of the comparative graph 600 of FIG. 6, one approach toreducing the effects of sunlight on the optical response signal 111(FIG. 1) is to choose an optical emitter 102 (FIG. 1) that emits lightat wavelengths shorter than 600 nm and to choose an optical detector 103(FIG. 1) having an optical filter that blocks light having wavelengthslonger than 600 nm or that passes light within an optical bandwidthprovided by the optical emitter 102 (FIG. 1). For example, a 400 to 500nm optical emitter 102 (FIG. 1) may provide 400-500 nm opticalexcitation 110 (FIG. 1) to the ear region 130 (FIG. 1), and an opticaldetector 103 (FIG. 1) having a 400-500 nm optical filter may be used todetect the energy response signal 111 (FIG. 1) with low interference 140(FIG. 1) from sunlight. While this method may be employed, the apparentbenefits may be deceiving because the intensity of the optical scattersignal associated with physiological information may be orders ofmagnitude smaller than the sunlight interference—even with the combinedattenuation effects of the optical filtering method and the strategicsensor module placement between the earbud housing and ear region (asshown in FIGS. 4 & 5). A better approach for attenuating the opticalinterference signal may be to employ optical filters within the opticaldetectors 103 such that the only wavelengths passing into an opticaldetection window may be wavelengths that are naturally attenuated by theearth's atmosphere. For example, there are several attenuation bands forsunlight well-known in the art due to the absorption of sunlight by O₂,O₃, CO₂, and H₂O in the atmosphere. The sharp absorption peak near 763nm in FIG. 6 is just one example. Thus, a novel design for rejectingsunlight interference may incorporate at least one optical emitter thatgenerates optical wavelengths within at least one sunlight attenuationband combined with at least one bandpass-filtered optical detector,incorporating at least one optical bandpass filter to pass onlywavelengths falling within this attenuation band.

Sunlight is quite powerful and intense, and any sunlight reaching anoptical detector 103 (FIG. 1) may completely saturate the detector 103and make it virtually impossible to extract a physiological signal fromthe optical scatter signal 111 (FIG. 1) coming from the human body.Unfortunately, it may be difficult to make a plastic or metal earbudhousing light-tight under standard commercial manufacturing processes.For example, most commercial audio headsets include a housing made ofplastic, and this plastic may be molded to include clamshells forassembly. Furthermore, commercial earbuds may be composed of multipleseparate pieces that must be aligned and snapped together or adhesivelyattached. However, the longer wavelengths of sunlight, especially IRlight, can leak through such plastic material, the clamshell regions ofthe plastic housing, or the bordering regions between separate plasticpieces. Furthermore, many audio headsets require openings in thematerial between the earbud housing and audio speaker cavity such thatsound can travel freely between the tympanic membrane and the audiospeaker. Sunlight may also travel between these small openings andundesirably reach the detector 103. Sunlight scattering from unwantedopenings in the plastic enclosure may scatter within the clamshells ofthe enclosure and reach the optical detector 103.

According to some embodiments of the present invention, a sensor module700 with an overmolded design, as shown in FIG. 7, may be employed toremedy the problems associated with sunlight leaking towards the opticaldetector 103. In this design, an overmold layer 740 surrounds thecomponents of the sensor module 700 to prevent light leakage into anyspot along the periphery of the sensor module 700. The overmold layer740 comprises a light-opaque material surrounding the optical emitter102 and optical detector 103 such that the optical emitter 102 andoptical detector 103 are not in direct optical communication with eachother. The light-opaque material of the overmold layer 740 may include afirst aperture 740 a in communication with the optical emitter 102, anda second aperture 740 b in communication with the optical detector 103.Thus, the only device regions having access to outside light may be theregions of the optical emitter 102 and detector 103, but these may becovered by at least one optical filter 710 tuned to a wavelength regionof interest. If utilized, the wavelength pass-band of an optical filtercovering the emitter 102 should be tuned to the emitter wavelength bandso that all other light is blocked. If utilized, the wavelengthpass-band of the optical filter 710 covering the detector 103 should betuned to at least one wavelength band associated with the opticalscatter 111 (FIG. 1) of interest from the medium 130 (FIG. 1) so thatall other light is blocked.

In some embodiments of the present invention, an optical filter for theemitter 102 and detector 103 may be the same filter, such as may be thecase for optical scatter 111 (FIG. 1) detection by the detector 103where all light other than the emitter light of interest may be blockedby the filter 710. According to some embodiments of the presentinvention, the optical filter 710 covering the detector 103 isconfigured to block unwanted sunlight but still allow wavelengths fromthe optical emitter 102 to pass therethrough. In some embodiments of thepresent invention, the optical filter 710 over the detector 103 isconfigured to pass wavelengths centered around 930 nm, and the opticalemitter 102 is configured to emit wavelengths centered around 930 nm.According to some embodiments of the present invention, the opticalfilter 710 may have a surface area greater than a surface area of theoptical detector 103. In some embodiments of the present invention, theoptical filter 710 overlies the optical detector 103 such that aperiphery of the optical filter 710 overlaps a periphery of the opticaldetector 103, as shown in FIG. 7 and FIG. 8.

To guide light from the optical emitter 102 towards the skin 130 of asubject and to direct light from the skin 130 to the optical detector103, lenses 715 may be utilized, as illustrated in FIG. 7. The lenses715 may be physically separated lenses (as shown in FIGS. 7 and 8) orcombined or conjoined lenses. In some embodiments of the presentinvention, there is no optical coupling between the emitter lens 715 anddetector lens 715. For this reason, a barrier region may be incorporatedin the case where the lenses are combined or conjoined. Separated lensesmay be isolated by at least one light opaque barrier region greater than50 μm in thickness. Light opaque plastic, rubber, metal, or polymericmaterial are a few examples of good choices for the light opaque region.The optical lenses 715 may be designed for the desired optical couplingbetween the skin/blood vessel region and the emitter 102 or detector103. For example, a convex lens design (such as that of FIG. 7) placedover the emitter 102 may focus light onto the skin, and a concave lensdesign (such as that of FIG. 8) placed over the emitter 102 may divergelight over the skin region. In the other direction, a convex lens designplaced over the detector 103 may capture more light over a broaderregion and direct that light towards the detector 103, whereas a concavelens may collimate light towards the detector 103.

The optical lenses 715 may be separate from the overmold layer 740 ormay be part of the overmold layer 740. For example, the overmold layer740 may be comprised of material that is transparent to light 110(FIG. 1) coming from the emitter 102. In such case, the lenses 715 mayintegral with the overmold layer 740. In other cases, the optical lenses715 may be comprised of different material than the overmold layer 740,such that the lenses 715 may fit within the overmold layer 740 and bematingly engaged with the overmold layer 740.

As shown in FIGS. 7 and 8, the emitter 102 and detector 103 may beintegrated within a circuit board 720 assembly, such as a printedcircuit board (PCB) assembly. The PCB board 720 may have opposite firstand second sides 720 a, 720 b, with at least one optical emitter andoptical detector adjacent to each other on the first side 720 a, andwith at least one secondary sensor 730 on the second side 720 b. Thesecondary sensor 730 may be integrated within the PCB 720 for sensinganother parameter. In one particular embodiment, the secondary sensor730 may serve as a motion/position sensor 104 (FIG. 1). Connections orwiring 750 may be used to connect the sensor module 700 to anotherapparatus, connector, PCB, circuit, or the like. For example, electricalwiring or fiber optic cables may be overmolded such that sunlight cannotpass through the interface between the wires/cables and the overmoldlayer 740.

Another benefit of the overmolded design of FIGS. 7 and 8 is that it mayalso provide resistance to water, humidity, sweat, wind, and otherenvironmental interferants. For example, an overmolded plastic designaround the emitters 102 and detectors 103, combined with overmolded orglued lenses 715, may at least partially encapsulate the emitters 102and detectors 103 and hence at least partially isolate these devicesfrom the environment.

FIGS. 9A and 9B illustrate an environmentally protected earbud 900 thatcan incorporate overmolded sensor modules 700, 800, according to someembodiments of the present invention. In the illustrated embodiment, atleast two sensor modules 700 are shown to emphasize that multiple sensorlocations can be used, as long as the sensor modules 700 are configuredto direct energy towards the ear and detect the energy response from theear. Additionally, having multiple sensor modules 700 located around theearbud housing 901 may help with: a) making the environmentallyprotected earbud 900 work uniformly well on a variety of persons havinga variety of differing ear physiology and/or b) enabling additionalsensor functionality, such as the ability to sense blood gas levels,blood metabolite levels, pulse pressure, blood pressure, glucose, and avariety of other physiological metrics or analytes. At least onesupporting arm 902 may be connected to the earbud housing 901 to supporta wire, electrical connections, and/or provide additional support aroundthe ear. For example, a supporting arm 902 may be used to house wires orwrapped around the ear to further support the earbud housing 901 withinthe ear.

In some embodiments of the present invention, an additional opticalfilter (e.g., 710, FIGS. 7 and 8) may be utilized that serves (or alsoserves) as an attenuation filter, such as a “neutral density filter”,gelatin filter, opaque material, or other optical attenuation filter orfiltering materials. In one embodiment, an optical filter 710 may serveas both an optical wavelength filter and an attenuation filter. Becausesunlight is so powerful, it may be beneficial to reduce sunlightinterference as much as possible, even if that means also reducing theamount of optical scatter 111 (FIG. 1) of interest from the medium 130(FIG. 1). To offset this unwanted reduction in optical scatter 111, theintensity of the optical emitter 102 may be increased to increase theratio of physiological optical scatter 111 from blood vessels withrespect to unwanted sunlight.

The angling of the sensor modules 700, 800 (FIGS. 7 and 8) within theearbud housing 901 may be designed to direct light towards the ear anddetect light from the ear while rejecting as much environmental light(such as sunlight) as possible. As shown in FIG. 10, angling the normal“N” of the lens 715 between the perpendicular lines “A” & “B”, where “A”is perpendicular to earth ground and “B” is parallel to earth ground,would help achieve this goal. Phrased another way, the angle “θ_(N)”between “N” and “A” or “N” and “B” would preferably be less than 90°.The lens 715 placement and angle does not obstruct the audio cavitybetween the speaker 910 and the earbud housing opening(s) 903, whichhelps couple light to the ear canal. For this reason, in some cases,angle “θ_(N)” approximating 45° may be utilized for limiting the sensormodule 700 exposure to outside light while also limiting the obstructionof the audio cavity by the sensor module 700.

The lenses 715 described herein may be comprised of any material that isat least partially transparent to the wavelengths of light generated bythe emitter 102 and/or the desired wavelengths of light detected by thedetector 103. In some embodiments of the present invention, the lenses715 are completely transparent to the light of interest, but in otherembodiments of the present invention the lenses 715 may be configured todiffuse, attenuate, disperse, or redistribute light uniformly across thelens. For example, a lens 715 incorporating diffusing material, placedover the emitter 102, may help spread more light from the emitter moreuniformly across the area of the lens such that a broader physiologicalregion may be excited by optical radiation. Similarly, a diffusing lensconfiguration placed over the detector 103 may help detect light from abroader area of the body and direct that light towards the detector 103.Some plastic materials contain scattering centers or materials that tendto scatter light. For example, silicones may be used to diffuse light ina lens. Partially opaque lenses may also be used to provide diffusion orinternal scattering of light within a lens. Additionally, roughenedsurfaces, such as roughened plastic or glass, may encourage diffuseoptical scatter without greatly attenuating the intensity of light.Other methods of creating optical diffusion or scattering inlight-guiding materials such as lenses may be utilized.

The angled emitter-detector earbud configuration 1100 of FIG. 11 may beemployed to maximize the collection, by the detector 103, of thescattered light response 111 (FIG. 1) related to physiologicalconditions and to minimize the collection of the unwanted scatteredlight response 111 (FIG. 1) not related to physiological conditions.Angling the emitter 102 with respect to the detector 103 can preventunwanted light generated by the emitter, such as that scattered by theouter surface of the skin, from reaching the detector 103. While at thesame time, desired light that is guided into the blood vessels,scattered within physiological material 130, and coupled into thedetector 103 may contain desired optical information associated withphysiological changes. The higher the angle between the emitter andetector, the less the intensity of optical energy that may be detectedby the detector 103. However, the higher the angle, the higher the ratioof desired optical signal to undesired optical signal. In someembodiments of the present invention, the angle between the normal“N_(e)” of the optical emitter and the normal of the optical detector“N_(d)” is between 0° and 90°. The position of the emitter 102 anddetector 103 as shown in FIG. 11 may be reversed, providing the sameeffect. However, the optical emitter 102 may be located near the portionof the ear having a higher density of blood vessels, such that theoptical energy will be more greatly modulated by physiologicalconditions (such as blood flow, blood gas levels, and the like) and suchthat the optical energy detected by the detector 103 will be moreindicative of physiological conditions and less indicative of unwantedoptical scatter (such as skin reflectance) or motion-related scatter(such as motion caused by running, jogging, or talking).

It should be noted that the angling of the emitters 102 or detectors 103in the right location within not only the earbud housing 901, but alsowithin the ear itself, may be critical for blocking out sunlight 140while still generating a strong enough physiological signal from the earregion. For this reason, the earbud 1100 (FIG. 11) may also employ atleast one earpiece fitting, or other additional mounting support, tokeep the earbud in place within the ear and/or keep the sensor module700, 800 directed at the right angle within the ear. Several types ofearpiece fittings are well known in the art, such as: ear hooks, earclips, ear pads, ear loops, concha support, headbands, and the like. Aspecific example of a supportive earpiece fitting, a concha support thatloops around the concha-helix area of the ear, is shown in the earbud404 of FIG. 4. In some embodiments of the present invention, theearpiece fitting supports the earbud within the ear while also placingpressure against the earbud to keep the sensor module in place, awayfrom outside light interference.

At least part of the earbud housing 901 (FIG. 11) or sensor module 700(FIG. 11) may comprise a soft material which deforms when insertedwithin the ear and that facilitates retention of the earbud within theear. For example, the shape of earbud housing 901 shown in FIG. 11 mayfacilitate retention of the earbud 1100 within the ear because it may beshaped to mate or engage with the concha or outer ear canal of the ear.Furthermore, if part of the earbud 1100 comprises a soft material, suchas soft plastic, polymer, silicone, or rubber, the material may deformwhen the earbud 1100 is inserted within the ear such that this part ofthe earbud 1100 mates or engages with the ear. The sensor modules ofFIGS. 7 and 8 may be integrated within the earbud housing 901, such thatat least a portion of the housing 901 may comprise opticallytransmissive material to allow light to move from the emitter 102 to theear region or from the ear region to the detector 103. The softdeforming material may be adjacent to the optically transmissivematerial or may comprise at least part of the optically transmissivematerial itself. For example, the lenses 715 of FIG. 9 may be comprisedof optically transparent material that is also soft, such as silicone ortransparent plastic, polymer, rubber, or the like. In anotherembodiment, a second layer of soft, yet transparent, material may coverthe lenses 715.

An exemplary overmolding configuration of a sensor module 1201 isillustrated in FIGS. 12A-12C. The sensor module 1201 is shown without anemitter, detector, or lenses, but rather with recesses/apertures 1202showing where lenses may be located. Exemplary dimensions are alsopresented in FIG. 12. In some embodiments of the present invention,dimensions are on the order of millimeters or less, such that the sensormodule 1201 can fit within a small-sized earbud without obstructing, orminimally obstructing, the audio cavity. In the illustrated embodiment,an emitter and detector to be used with the sensor module 1201 can bearranged in a line that is parallel with the antitragus. Thisarrangement is illustrated in FIGS. 13A-13C. However, embodiments of thepresent invention are not limited to any particular set of dimensions orto any shape or configuration.

FIG. 14 illustrates a multi-detector earbud 1400, similar to the earbud1300 of FIGS. 13A-13C, but where two separate optical detectors (notshown) are covered by two separate optical lenses 715. An opticalemitter 102 is located between the two optical lenses 715. Employingmultiple optical detectors may provide several benefits: 1) morescattered light collection, providing stronger signal strength, 2)additional information on scattered light collection for improvingphysiological assessments, 3) light collection at different wavelengthsfor measuring blood constituents, pulse pressure, skin, color, and thelike, and 4) other benefits. For example, light entering the ear mayscatter throughout several blood vessels, and without multipledetectors, signal information may be lost. Additionally, blood flowscatter collected from the front of the ear may be more indicative ofblood flow through the carotid artery system, whereas blood flow scattercollected from the back of the ear may be more indicative of thecapillary or venous system. The difference between these two signals maybe processed with algorithms to generate an assessment of pulsepressure, blood pressure, cardiac output, and the like. Lastly,collecting light at different wavelengths, and processing these signalscollectively, can be used to generate assessments of blood gas levels,such as blood oxygen (SpO₂) and carbon dioxide (SpCO₂), blood hemoglobintypes and levels, or other blood constituents and their respectiveconcentration levels. Multiple wavelengths may be generated by a signalmultiwavelength optical emitter, multiple optical emitters, opticallyfiltered optical emitters, or the like. In such case, multiple opticalemitters 102 may be located between the two optical filters 715.

FIGS. 15A-15B show a multi-detector earbud 1500, where two separateoptical detectors 103 are covered by two separate optical lenses, atleast one optical emitter is covered by at least one optical lens, andwhere the emitter 102 and detector 103 configuration is orientedperpendicularly to the antitragus (as that shown in FIG. 11). In FIGS.15A-15B, the optical detectors 103, emitters 102, and lenses are notreadily visible as they are surrounded, at least in part, by an opticalcoupling area 1510. The lenses (not shown) may cover each separateemitter 102 and detector 103 as shown in FIGS. 7 and 8. Note that inthis configuration, the emitter-detector module 700, 800 of FIGS. 7 and8 is oriented towards the back of the ear (near the back of the head).This arrangement may serve two purposes: 1) sunlight may be furtherblocked from reaching the detectors 103, as the back of the ear mayserve as a shield and 2) there may be less motion artifacts convolutingthe desired blood flow signals, as the detectors 103 may be orientedaway from mouth-motion-prone areas located near the front of the ear.Another feature of the earbud 1500 of FIGS. 15A and 15B is that anoptical coupling area 1510 is located on top of the optical emitter 102and surrounding (but not covering) the optical detector 103. Thisoptical coupling area 1510 may help diffuse, scatter, and/or guide lightfrom the optical emitter to couple with a broader area of the earregion. Having a broader coupling area may help excite more regions ofthe ear with optical energy 110 (FIG. 1) and reduce the chance that theoptical energy may miss important blood vessels, which may be located indifferent regions for different persons. Thus, such a design may promotea more universal design for a biometric earbud. Without an opticalcoupling area 1510, the optical energy 110 from the optical emitter(s)102 may miss blood vessels in different persons due to physiologicaldifferences that may exist between different people. Alternatively, theoptical coupling area 1510 may be configured to cover the opticaldetector 103 area and not the optical emitter 102 area, such that morelight is guided from different regions of the ear and coupled into thedetector 103. Alternatively, a plurality of optical diffusion areas maybe configured to cover the emitter 102 and detector 103 separately.

The material selection for the optical coupling region 1510 may be anytype of optically transmissive material. For example, a plastic, rubber,silicone, or other soft, moldable material may be used. In someembodiments, the material may intentionally contain scattering centersor may contain partially opaque regions to promote optical scatter andgenerate a uniform, diffuse optical beam across the optical couplingarea 1510. In some embodiments, the material may be roughened, as withroughened plastic or glass, to generate scattering centers.

FIGS. 16A-16B illustrate an exemplary headphone 1600 having areplaceable/interchangeable earbud tip 1601. An interchangeable tip 1601can provide the benefit of allowing larger or smaller tips on the end ofthe earbud housing 901 to accommodate larger or smaller ears. A typicalcommercially available headphone structure may look like the embodimentillustrated in FIG. 16A. In FIG. 16B, an optical sensor module 700 isintegrated into the bottom of the headphone housing 901, in the regionnear the antitragus, in a form-fitted shape 1610 designed to makecontact with the antitragus region. However, this may increase the sizeof the housing by a few millimeters in multiple dimensions. For thisreason, the interchangeable earbud tip 1601 may be modified with aform-mating region 1612 to mate with the form-fitted region 1610 andthus accommodate the change in size imposed by the optical sensor module700.

According to other embodiments of the present invention, opticalcoupling and waveguiding are incorporated into a headphone. For example,at least one emitter (not shown) and at least one detector (not shown)may be integrated into a sensor module and stationed within an earbudhousing 901 of the headphone 1600 of FIG. 16A without the addition of aform-fitted shape 1610 (FIG. 16B) or mating region 1612 (FIG. 16B).Optical excitation of the ear region can be generated by guiding lightfrom an emitter to an interchangeable earbud tip 1601 and into the earregion or by guiding scattered light from the ear region into the earbudtip 1601 and into an optical detector. To couple light from an opticalemitter into the earbud tip 1601, the optical emitter may be positionedin the earbud face 1605 region to direct light towards the earbud tip1601. In some embodiments of the present invention, the optical detectoris positioned in the earbud bottom region 1606 (FIG. 16A) to receivelight from the bottom of the ear. Similarly, to couple light from theearbud tip 1601 to an optical detector, the detector may be located inthe front earbud face region 1605 (FIG. 16A) to receive light from theearbud tip 1601.

In some embodiments of the present invention, the optical emitter ispositioned within the earbud bottom region 1606 (FIG. 16A). Using theinterchangeable earbud tip 1601 as a light guide, the earbud material ismade of at least partially transparent materials, which are transparentto the wavelength of interest. Additionally, an earbud material having ahigher index of refraction than air may be used so that more light isguided along the earbud tip 1601 and less light is scattered away fromthe earbud tip 1601. Additionally, intermediate regions between theearbud face 1605 and the earbud tip 1601 may be utilized in order topromote optical coupling between the two regions. For example, a lens(not shown) or other light guiding region may be placed over theemitters or detectors to promote this optical coupling.

Referring to FIG. 16B, in some embodiments of the present invention,emitter(s) and detector(s) may both be positioned in the earbud face1605 region to direct light towards the earbud tip 1601. In this manner,the earbud tip 1601 may help: 1) direct light from the emitter to theear region and 2) direct light from the ear region to the detector.However, optical scatter interference associated with light from anemitter bouncing around in, around, and about the earbud tip 1601 mayconvolute a desired optical scatter signal (e.g., 111, FIG. 1)associated with physiological information (such as blood flow in the earregion). To reduce this unwanted convolution of undesired opticalscatter, the earbud tip 1601 may include at least two separate parts, asshown in FIG. 17. The earbud tip 1601 illustrated in FIG. 17 isseparated by an optical barrier 1710, with one part coupled to theoptical emitter and another part coupled to the optical detector. Eachpart may support at least one separate optical path isolated by at leastone optical barrier 1710. For example, one part may direct light fromthe emitter to the ear region and another part may direct light to thedetector from the ear region. The optical barrier 1710 may be anymaterial that is partially or completely opaque to the light wavelengthof interest or any interface which reduces light transmission orcommunication between the two earbud tip parts. For example, the earbudtip 1601 may be molded from two (or more) separate materials (plastic,rubber, silicone, and the like) separated by: 1) an opaque material(plastic, rubber, silicone, paint, and the like) or 2) at least oneinterface between the two (or more) separate materials. The interfacemay be as simple as the natural interface between the two separatematerials or as complex as by specially treating the interface by heat,light, abrasion, dissolving, chemical application, or the like. Aroughened interface may help scatter light away from the interface andhelp keep the optical paths isolated within each respective part. It isimportant to note that such a multi-part earbud tip design may require amating region 1612 to help align the earbud coupling part and detectorcoupling part with the emitter(s) and detector(s) respectively. As afurther note, this design should not be limited to the two earbud tipparts (the emitter coupling part and detector coupling part) shown inFIG. 17. In one embodiment, multiple earbud tip parts may be employed todirect light from multiple separate emitters and/or multiple separatedetectors located along the earbud housing 1901. Moreover, multipleseparate materials may be used in each part, such that each part mayprovide different optical filtering or conditioning properties. Such adesign may be particularly important for multiwavelength spectroscopy ofthe ear region.

An exemplary filter processes samples 1910, the off/on samples 1920/1930respectively, taken from a digitized physiological sensor signal 1911generated by a detector (e.g., 103, FIG. 1) as shown in FIGS. 19A-19B. Apulsed emitter (e.g., 102, FIG. 1) generates a pulsed beam of light suchthat some samples 1920 represent signal 1911 from a detector with theemitter turned off and other samples 1930 represent signal 1911 from thedetector with the emitter turned on. Both types of samples 1920 and 1930may contain environmental noise from environmental interferants, butonly emitter-on samples 1930 contain physiological information generatedby the emitter energy. The digitized samples taken from detector signal1911, provided by an ADC (e.g., 105, FIG. 1), are processed by aninterference filter (e.g., 106, FIG. 1) and the output of theinterference filter may be directed for further processing (representedby 107, FIG. 1).

These operations are summarized in FIG. 18, which is a flow chart ofoperations for removing environmental noise from a sensor signal via aninterference filter, according to some embodiments of the presentinvention. At Block 1800, at least one ADC sample is read when theemitter is on. At Block 1802, at least one ADC sample is read when theemitter is off. At Block 1804, relevant on/off samples are input to aninterference filter. At Block 1806, at least one sample from theinterference filter is output for further processing.

An interference filter (e.g., 106, FIG. 1) utilized according toembodiments of the present invention, may vary in nature and complexity.For example, an interference filter may subtract temporally neighboringemitter-off samples 1920 (FIG. 19A) from temporally neighboringemitter-on samples 1930 (FIG. 19A) and output a “subtraction” signal forfurther processing. In this embodiment, the subtraction may involvesubtracting temporally neighboring on/off samples, averaging temporallyneighboring on samples and averaging temporally neighboring off samplesand then subtracting the average off samples from the average onsamples, or by other approaches to subtracting off signals 1920 from onsignals 1930. When choosing a subtraction approach, it is important toconsider the emitter pulsing frequency and sampling approach. Forexample, choosing a frequency that is too low may result inunsatisfactory subtraction, as the dynamic environmental conditionsbetween off-states 1920 and on-states 1930 may be too abrupt for thesampling frequency, such that the physiological state of interest is notproperly characterized by the interference filter. Thus, the samplingfrequency may need to be much higher than the Nyquist frequency requiredfor characterizing the signal in a stationary environment. As a specificexample, if an interference filter (e.g., 106, FIG. 1) is being used toremove sunlight interference (e.g., SL₁, SL₂, FIG. 3), from aphotoplethysmogram 1911 (FIGS. 19A, 19B), and if the desired processedoutput from the final filtering is heart rate, then the Nyquist criteriafor pulsing the emitter may be 2×f_(max), where f_(max) is the maximumheart rate of interest, which is likely to be somewhere around 200beats/minute (BPM) or 3.33 Hz.

However, a person running through alternating shadows may generate asunlight interference frequency greater than 10 Hz. In such case, it maybe desirable to select a sampling frequency greater than twice thesunlight interference frequency, which in this case would be greaterthan 20 Hz. Samples that are temporally neighboring (located close toeach other in time) may be averaged in this case to help remove noiseassociated with unintended transients. For example, the off samples 1920(FIGS. 19A, 19B) that come before, and/or after, a given on sample 1930(FIGS. 19A, 19B) may be averaged and then that average may be subtractedfrom the on sample 1930 (or average of the on samples), and this finalresult may be passed along for further processing.

As another example, a batch of data may be defined to consist of: 1) aset number of on/off optical detector samples, for instance 6interleaved on/off samples, 2) a set number of motion sensor samples,for instance 3 samples (one for each on/off optical sample), and 3) atime delay. The time delay may be adjusted to generate the desired batchrate or batch frequency. The 6 on/off optical samples may be input to amulti-tap filter, for instance an M-tap weighted sum filter, and theoutput may be defined as 1 output per batch for the interference filter.If the optical on/off samples are extended to fill the whole batchperiod by “N” samples, then the decimation factor is “N”, and theeffective sample rate is N*batch rate. The parameters for adjustment inthis filter may then be N and M, where M is the number of taps in thefilter. The batch rate may be chosen to avoid aliasing of interferingharmonics from the desired physical condition monitored, such as theheart rate. For example, batch rate may be chosen as 10*HRmax, whereHRmax is the maximum heart rate to be measured. The batch rate maydominate the MIPS (million instructions per second) used by a signalprocessor, such as a DSP (digital signal processor), since it affectsthe spectral transform of the desired output signal. In this filteringembodiment, to minimize aliasing from interfering sunlight-shadowchanges on the desired heart rate output signal (especially for runningor cycling through shadows), a increasing the N and/or M may bepreferred.

Another example of a batch may include nine (9) optical segments perbatch: off-on-off-on-off-on-off-on-off. Within a given batch, theaverage of the “off” samples may be subtracted from the average of the“on” samples, providing one output per batch. This would generate adecimation factor of nine (9). Additional batch configurations andon/off configurations may be used in this invention.

It should be noted that the modulated light 110 may be pulsed completelyon or completely off, or it may be pulsed partially on or partially off.In some embodiments, for example, the modulated light may be sinusoidal.A benefit of complete on/off pulsing is that it may better-facilitatethe signal processing methodologies outlined herein for attenuatingenvironmental noise and motion-coupled environmental noise from one ormore output signals.

A finite impulse response (FIR) version of an interference filter,according to some embodiments of the present invention, levering thepulsed-emitter on/off sampling rate, is presented in FIG. 20 andidentified as 2000. The illustrated interference filter 2000 employs adelay of “n” samples according to Z^(−n). Coefficients in the filter“b_(n)” allow multi-tap filtering. Pulsing an emitter (e.g., 102,FIG. 1) and selectively sampling on/off signals, as described herein,may modulate the physiological signal to a higher frequency. Thus, theoutput y(n) of the interference filter 2000 may be decimated todemodulate the output back into the baseband. A specific example of adecimation-by-2 algorithm may reject odd-numbered samples such that thedecimated signal, w(m), may be described by even-numbered samplesaccording to w(m)=y(2*m).

Examples of filters embodying the interference filter 2000, for removingsunlight interference from a PPG signal 1911 (FIGS. 19A, 19B) to extractheart rate, according to embodiments of the present invention, areillustrated in the plot 2100 of FIG. 21. The plot 2100 presents themagnitude response (in dB) for each interference filter vs. normalizedfrequency (1=Nyquist). Also shown in FIG. 21 is a representation of themodulated heart rate 2160 modulated by the emitter on/off sample rate,the demodulated heart rate 2140 demodulated by decimation, and theinterference frequency associated with dynamic sunlight noise 2150. As aspecific example for the previously described “subtraction filter” 2110,the FIR coefficients may be [b1 b2]=[1 −1]. A filter 2120 forsubtracting the temporally neighboring off-samples 1920, coming beforeand after a given on-sample 1930, may employ coefficients of [−0.05 1−0.5]. A filter 2130 using multiple on/off samples may employcoefficients of [−0.07 0.3−0.6 0.6−0.3 0.07].

It should be noted from FIG. 21 that interference filter 2000 may rejectmore unwanted sunlight than less complex filters. Because the dominantsunlight noise frequencies 2150 may be located at lower frequencies, andbecause the modulated heart rate signal frequency 2160 may be located ata much higher frequency, most or all of the sunlight noise 2150 may berejected by the interference filter 2130. Then through demodulation infurther-processing (e.g., 107, FIG. 1), the heart rate signal may bereturned to the baseband so that real-time heart rate may be extracted.

An interference filtering method, according to some embodiments of thepresent invention, may employ a motion/position sensor (e.g., 104,FIG. 1) to further remove interference from a desired physiologicalsignal (e.g., 109, FIG. 1). For the case of sunlight interference (e.g.,140, FIG. 1) on an earbud sensor module (e.g., 207, FIG. 2), outdoorsunlight may more strongly illuminate an ear and detector 103 in thesensor module 207 than the emitter 102 in the sensor module 207. Whilean interference filter (e.g., 2130, FIG. 21) may effectively remove thebaseband frequencies of this interference, harmonics caused bymotion-induced sunlight noise may dominate the digitized signal near thefrequencies of the modulated desired information (e.g., 2160, FIG. 21).The step rate of a person running or jogging may be the strongestcomponent of this interference. Moreover, because a person running orjogging may be moving through varying sunlight intensity, theinterference signal may be a convolution of motion-coupled-sunlightchanges in time. A technique for removing sunlight interference,according to some embodiments of the present invention, utilizes amotion or position sensor (e.g., 104, FIG. 1), such as an inertialsensor, accelerometer, pedometer, gyroscope, microelectromechanicalsensor, capacitive sensor, inductive sensor, optical motion sensor, orthe like. The step rate may be measured as the peak frequency in thespectrum of the signal coming from motion/position sensor 104 or as thefrequency of the spectral peak of the signal coming from themotion/position sensor 104. For example, the processed spectrum mayemploy differentiation or integration to generate a processedmotion/position signal, and the peak frequency of this processedspectrum may be more indicative of the step rate. Harmonics and aliasedharmonics of the step rate may determine the frequencies of interferenceto ignore in the desired-information spectrum. For example, the emitterpulse rate minus eight times the step rate (aliased 8th harmonic) may bethe frequency of strong interference in the frequency space of themodulated heart rate (e.g., 2160, FIG. 21), and frequencies within apre-determined range may be set to zero in the desired-informationspectrum.

It should be noted that a motion/position sensor (e.g., 104, FIG. 1)utilized in accordance with some embodiments of the present inventionmay come from a broad range of sensors: inertial sensor, accelerometer,pedometer, gyroscope, microelectromechanical sensor, capacitive sensor,electrical sensor, inductive sensor, optical motion sensor, or the like.This is because many types of sensors may be either intentionally orunintentionally sensitive to motion and/or position. However, in someembodiments of the present invention, a sensor 104 (FIG. 1) and/orprocessing algorithm are utilized that can identify motion signals fromphysiological, environmental, or other signals not directly associatedwith motion. In some embodiments of the present invention, at least oneoptical detector (e.g., 103, FIG. 1) may also serve as a motion sensor.Motion-related changes in scattered light (e.g., 111, FIG. 1) may beseveral times greater than blood-flow related changes in scatteredlight. Thus, the output of at least one detector 103 may be processedwith a digital filter, such as a spectral filter, adaptive filter,threshold filter, or the like, to identify only motion-related signalsand remove these signals from the desired response (e.g., 109, FIG. 1).Such processing may identify motion-related signals fromphysiological-related signals. In some embodiments of the presentinvention, by employing multiple optical detectors (e.g., 102, FIG. 1),motion-related signals may be identified from physiological-relatedsignals by processing signals from the multiple detectors using analgorithm, such as a spectral algorithm. An example of a spectralprocessing algorithm for identifying motion-related signals, accordingto some embodiments of the present invention, is to generate a spectralrepresentation of all signals in all detectors (e.g., 102, FIG. 1),identify key frequencies in each signal, and subtract, reduce, or removeall frequencies in common with each detector output. This type offiltering technique may work well because physiological signals maygenerate similar spectral peaks for all detectors (e.g., 102, FIG. 1)but motion signals may generate dissimilar spectral peaks in at leastone detector (e.g., 103, FIG. 1). Another example of processing thedetectors (e.g., 102, FIG. 1) to identify and remove motion-relatedsignals is to position at least one detector in a location that does not“see” optical scatter (e.g., 111, FIG. 1) from the body/ear region butinstead sees optical scatter from the earbud housing (e.g., 901, FIGS.9A, 9B) or other material that may move in synchronization with thebody. For example, the secondary sensor 730 (FIG. 7) may be an opticaldetector that measures light scattered from the earbud itself; becausethe sensor 730 may be facing the earbud and not the ear, only lightscatter from the earbud may be detected.

FIGS. 22A-22D are graphs of a processed heart rate signal output 109 ofan earbud module (e.g., earbud module 207, 700, FIGS. 2, 7) employingtwo different filter configurations, according to some embodiments ofthe present invention. The graphs illustrated in FIGS. 22A-22D weregenerated from data collected from a user wearing an earbud (e.g., 404,FIGS. 4A, 4B) during an outdoor run. FIGS. 22A and 22C show relativespectrograms of frequency vs. time, where the strongest spectral signalsshow the brightest relative intensities. FIGS. 22B and 22D show theestimates of step rate 2210 and heart rate 2220 following furtherprocessing 107 to extract the desired frequencies of interest. FIG. 22Ashows the spectrogram of the digitized sensor output from an opticaldetector (e.g., 103, FIG. 1) following the ADC process (e.g., 105,FIG. 1) without employing an interference filter (e.g., 106, FIG. 1).FIG. 22C shows the spectrogram of the same digitized sensor output ofFIG. 22A following signal processing via the interference filter 2130 ofFIG. 21. FIG. 22A shows a great deal of broadband noise from sunlight,the strongest signal appears to be the step rate signal 2210, and theheart rate spectrum 2220 appears very faint with respect to the steprate signal. In contrast, FIG. 22C shows substantially less broadbandnoise from sunlight, the strongest signal appears to be the heart ratesignal 2220, and the step rate signal 2210 appears very faint withrespect to the heart rate signal. Through further filtering (e.g., 107,FIG. 1), the heart rate 2220 and step rate 2210 may be extracted, asshown in FIGS. 22B and 22D. FIG. 22B shows that the estimated heart ratesignal 2200 is incorrect and does not match that of the spectrogramillustrated in FIG. 22A. In contrast, FIG. 22D shows that the estimatedheart rate signal 2200 is correct and does match that of the spectrogramillustrated in FIG. 22C. Namely, the advanced interference filter 2130is able to remove enough unwanted sunlight interference that the heartrate spectrum may be more easily extracted by spectral algorithms 107(FIG. 1) designed to pick out the strongest frequency as heart rate.

Monitoring apparatus, according to embodiments of the present inventioncan be adapted to fit around various parts of the body, such as an arm,leg, neck, etc. For example, monitoring apparatus, according toembodiments of the present invention can be implemented as a substrate,such as a wristband, armband, legband, neckband, waistband, ankleband,footband, handband, ringband, headband, or the like. The substrate maybe flexible and may be configured to surround all or a portion of a bodyof a subject. The substrate may be configured to be attached to a bodyof a subject adhesively, similar to a bandage. The location of a sensormodule (e.g., 700, 800) may be virtually any place along the skin of asubject; however, better PPG results may be obtained when a sensormodule is placed along an major artery.

Referring to FIGS. 23-29, an exemplary wristband monitoring apparatus2300 is illustrated. The wristband 2300 houses a power source,circuitry, a sensor module, and electronics as described above withrespect to the various earbud embodiments. As illustrated in FIG. 24, asensor module 700, 800 is positioned on the inside surface 2302 of thewristband 2300. The sensor module 700, 800 may include an isolationregion 2304 that is configured to keep the sensor module 700, 800 stablewith respect to the subject's wrist during use so as to reduce motionartifacts. The isolation region may be constructed out of any sturdymaterial, but for comfort, a foamy and/or flexible sturdy material maybe utilized. Furthermore, the isolation region 2304 may further shieldagainst environmental interference such as sunlight, externaltemperature, wind, and the like.

In some embodiments of the present invention, a light guiding region2306 may surround or partially surround the sensor module 700, 800and/or isolation region 2304, as illustrated in FIGS. 24-27. In FIGS.24-26, the light guiding region 2306 surrounds the sensor module 700,800. In FIG. 27, the light guiding region 2306 partially surrounds thesensor module 700, 800. The light guiding region 2306 helps direct lightto and/or from the sensor module 700, 800 and a blood flow region withinthe body part. In some embodiments, the light guiding region 2306 may bea reflector, such as a metal, metallic alloy, mylar, mica, reflectiveplastic, reflective textile, or the like. In other embodiments, thelight guiding region 2306 may be a transparent light guide, such astransparent silicone, polymers, rubbers, textiles, glass, epoxies,glues, or the like. In the case of a reflective layer, the sensor module700, 800 is at least partially exposed. In the case of a transparentlight-guiding layer, the sensor module 700, 800 may be completelycovered.

Referring to FIGS. 28 and 29, the sensor module 700, 800 may be tiltedwith respect to a body part region (e.g., the wrist area) of a subject.In the illustrated embodiments of FIGS. 28 and 29, the sensor module700, 800 is tilted towards the wrist (away from the upper arm). Theembodiment illustrated in FIG. 28 has a light guiding region 2306 with adifferent configuration from the light guiding region 2306 illustratedin the embodiment of FIG. 29. The tilting of the sensor module 700, 800serves at least the following functions: 1) protection from sunlight and2) improvement of coupling between light from the sensor module 700, 800and blood flow in the body part (i.e., wrist area). Sunlight immunitymay be improved in this fashion because a human's wrist is typicallypointed away from sunlight, and so pointing the sensor module down alongthe arm may help prevent environmental (i.e., sunlight) interference.Also, pointing the sensor module 700, 800 towards the wrist may increasethe surface area of blood flow exposed to the sensor module 700, 800,thus increasing the blood flow signal intensity for PPG and the like.

The processing of signals generated by the sensor module 700, 800 in thewristband embodiments of FIGS. 23-29 may be similar or identical to thatdescribed above with respect to the earbud embodiments.

The foregoing is illustrative of the present invention and is not to beconstrued as limiting thereof. Although a few exemplary embodiments ofthis invention have been described, those skilled in the art willreadily appreciate that many modifications are possible in the exemplaryembodiments without materially departing from the teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of this invention as defined inthe claims. The invention is defined by the following claims, withequivalents of the claims to be included therein.

That which is claimed is:
 1. A monitoring apparatus comprising: ahousing configured to be positioned within an ear of a subject; and asensor module disposed within the housing, the sensor module comprising:a printed circuit board (PCB) having opposite first and second sides; anoptical emitter attached to the first side of the PCB, wherein theoptical emitter directs modulated electromagnetic radiation at a targetregion of the ear; an optical detector attached to the first side of thePCB adjacent to the optical emitter, wherein the optical detectordetects an energy response signal from the subject that is associatedwith a physiological condition of the subject; an optical filteroverlying at least a portion of the optical detector, wherein theoptical filter attenuates time-varying environmental light interferenceat one or more selected wavelengths from the energy response signal,wherein the time-varying environmental light interference is caused bysunlight and/or ambient light; and at least one processor that controlsoperations of the optical emitter and/or optical detector.
 2. Theapparatus of claim 1, wherein the optical filter has a surface areagreater than a surface area of the optical detector, and wherein theoptical filter overlies the optical detector such that a periphery ofthe optical filter overlaps a periphery of the optical detector.
 3. Theapparatus of claim 1, further comprising at least one additional opticaldetector attached to the PCB second side.
 4. The apparatus of claim 1,further comprising a lens positioned above at least one of the opticalemitter and filter.
 5. The apparatus of claim 1, further comprisinglight-opaque material surrounding the optical emitter and opticaldetector such that the optical emitter and optical detector are not indirect optical communication with each other.
 6. The apparatus of claim5, wherein the light-opaque material includes a first aperture incommunication with the optical emitter, and a second aperture incommunication with the optical detector.
 7. The apparatus of claim 5,further comprising a lens positioned above the optical emitter andfilter, and wherein the lens includes respective first and secondportions configured to matingly engage the respective first and secondapertures in the light-opaque material.
 8. The apparatus of claim 5,further comprising a first lens positioned within the first aperture andin optical communication with the optical emitter, wherein the firstlens focuses light emitted by the optical emitter, and a second lenspositioned within the second aperture and in optical communication withthe optical detector, wherein the second lens focuses light toward theoptical detector.
 9. The apparatus of claim 1, wherein the housingcomprises a soft material which deforms when inserted within an ear andthat facilitates retention of the housing within an ear.
 10. Theapparatus of claim 1, wherein the housing comprises a shape thatfacilitates retention of the housing within an ear.
 11. The apparatus ofclaim 1, wherein a portion of the housing comprises opticallytransmissive material through which light from the optical emitter canpass, and wherein the housing comprises a soft material adjacent to theoptically transmissive material which deforms when inserted within anear and that facilitates retention of the housing within an ear.
 12. Theapparatus of claim 1, further comprising at least one speaker.
 13. Theapparatus of claim 1, wherein a portion of the housing comprisesmaterial configured to diffuse light from the optical detector and/ordiffuse light to the optical detector.
 14. The apparatus of claim 1,wherein the at least one sensor module also comprises at least onemotion/position sensor attached to at least one side of the PCB.
 15. Theapparatus of claim 1, further comprising an optical filter configured toprocess digitized time-varying environmental light interference signals.